A supercritical water gasification system and method for treating plastic waste slurry

Abstract

The present invention relates to the technical field of waste resource utilization, and discloses a supercritical water gasification system and method for treating plastic waste slurry. In the system, a coupled reactor device comprises a primary gasification reactor, an oxidation reactor and a secondary gasification reactor which are sequentially arranged from the outside to the inside; a gap is set between the bottom end of the oxidation reactor and the bottom end of the primary gasification reactor, and the bottom end of the oxidation reactor is provided with a through hole; a gap is set between the top end of the secondary gasification reactor and the top end of the oxidation reactor, and the top end of the secondary gasification reactor is provided with a through hole; the present invention forms an efficient gasification treatment process through the coupling arrangement of the primary gasification reactor, the oxidation reactor and the secondary gasification reactor, so that the plastic waste slurry can be gradually gasified at different reaction stages, thereby improving the gasification efficiency and conversion rate, thereby more effectively converting the plastic waste into usable gas resources.

Description

Technical Field

[0001] The present invention relates to the technical field of waste resource utilization, and in particular to a supercritical water gasification system and method for treating plastic waste slurry. Background Art

[0002] Amidst growing environmental challenges, plastic waste has become a global concern, posing a potential threat to ecosystems, wildlife, and human health. Due to its chemical stability and recalcitrance, traditional treatment methods often face numerous challenges. Traditional methods for disposing of plastic include landfill, incineration, and biodegradation. Landfill is relatively simple to operate and requires less technical and equipment expertise, but it occupies significant land resources. Furthermore, plastics degrade very slowly; a typical plastic bottle can take hundreds of years to fully degrade in the natural environment. During landfilling, harmful substances in plastics can enter the soil and groundwater through rainwater infiltration, contaminating them. Incineration can produce highly toxic, carcinogenic, and teratogenic gases, posing significant risks to the environment and human health. Biodegradable plastics are relatively expensive to produce, and their degradation rate is strictly limited by environmental conditions such as temperature, humidity, and microbial species.

[0003] As an emerging treatment method, supercritical water technology exhibits unique advantages. It combines the solubility of liquids with the diffusion capacity of gases. It can rapidly mix with organic matter and oxygen, accelerating chemical reactions and creating ideal conditions for the efficient decomposition and transformation of plastic waste. Water in a supercritical state possesses physical and chemical properties such as high solubility, high diffusivity, and high reactivity. It can rapidly break the chemical bonds of organic compounds in plastic waste, producing high-value gases such as hydrogen and methane through free radical reactions. Elements such as nitrogen and sulfur in plastic waste can synergistically solidify with ash in a reducing reaction environment, significantly reducing the environmental pollution caused by the emission of harmful gases and substances. Furthermore, supercritical water gasification technology can be combined with power generation and heating technologies to build a complementary system of multiple energy sources, enriching the energy supply system.

[0004] However, when the current supercritical water gasification technology is used to treat high-concentration plastic waste, the high concentration of plastic waste makes it difficult for supercritical water to fully penetrate, resulting in poor local mass transfer effect. The plastic molecules cannot contact the supercritical water evenly and smoothly, and some plastics collide and aggregate to form coke. Once formed, the coke will not only adhere to the inner wall of the reaction equipment, reducing the heat transfer efficiency of the equipment, but also block pipes and valves, hindering the output of plastic waste and the discharge of products.

[0005] In addition, supercritical water gasification is an endothermic reduction process. It takes a lot of energy to treat high-concentration plastic waste and maintain the supercritical state of high temperature and high pressure. During the reaction, the heat demand will vary with the different stages of the reaction, but the heating system is usually unable to provide enough heat in real time according to the reaction requirements, resulting in a mismatch between energy supply and reaction requirements, the reaction cannot proceed efficiently, and some energy is wasted. Summary of the Invention

[0006] In order to overcome the defects of the above-mentioned prior art, the purpose of the present invention is to provide a supercritical water gasification system and method for treating plastic waste slurry, so as to solve the technical problem in the prior art that high-concentration materials are difficult to efficiently gasify and efficiently heat in supercritical water.

[0007] The present invention is achieved through the following technical solutions:

[0008] In a first aspect, the present invention provides a supercritical water gasification system for treating plastic waste slurry, comprising a water preheating output unit, a slurry output unit, a liquid oxygen output unit, a coupled reactor device, a heat exchanger, a gas-liquid separation unit, and a heat circulation loop unit;

[0009] The coupled reactor device includes a primary gasification reactor, an oxidation reactor, and a secondary gasification reactor that are sequentially arranged from the outside to the inside; a gap is provided between the bottom end of the oxidation reactor and the bottom end of the primary gasification reactor, and the bottom end of the oxidation reactor is provided with a through hole; a gap is provided between the top end of the secondary gasification reactor and the top end of the oxidation reactor, and the top end of the secondary gasification reactor is provided with a through hole;

[0010] The output end of the water preheating output unit is provided with two branches, one of which is connected to the liquid input end of the primary gasification reactor, and the other is connected to the slurry output unit; the output end of the slurry output unit is provided with two branches, one of which is connected to the slurry input end of the primary gasification reactor, and the other is connected to the slurry input end of the secondary gasification reactor;

[0011] The output end of the liquid oxygen output unit is connected to the input end of the oxidation reactor, and the output end of the secondary gasification reactor is connected to the gas-liquid separation unit via a heat exchanger; the heat circulation loop unit is arranged on the heat exchanger for supplying heat to the outside.

[0012] Preferably, the water preheating output unit includes a water tank, a first flow regulating valve, a water pump and a solar heater;

[0013] The output end of the water tank is provided with two branches, one of which is connected to the liquid input end of the primary gasification reactor through the first flow regulating valve, the water pump and the solar heater in sequence; the other branch is connected to the slurry output unit.

[0014] Furthermore, the slurry output unit includes a plastic waste slurry tank, a mixer, a first plastic waste pump, and a second plastic waste pump;

[0015] The output end of the plastic waste slurry tank is connected to the input end of the mixer, a branch of the water tank is connected to the input end of the mixer, and the output end of the mixer is provided with two branches, one of which is connected to the slurry input end of the primary gasification reactor via a first plastic waste pump; the other branch is connected to the slurry input end of the secondary gasification reactor via a second plastic waste pump.

[0016] Furthermore, an eighth flow regulating valve is provided between the output end of the plastic waste slurry tank and the input end of the mixer; a sixth flow regulating valve is provided between a branch of the water tank and the input end of the mixer; a second flow regulating valve is provided at the output end of the mixer; a third flow regulating valve is provided between a branch of the output end of the mixer and the first plastic waste pump; and a fourth flow regulating valve is provided between another branch of the output end of the mixer and the second plastic waste pump.

[0017] Preferably, the liquid oxygen output unit includes a pre-processor, a liquid oxygen pump, a fifth flow regulating valve and a liquid oxygen tank;

[0018] The output end of the liquid oxygen tank is connected to the input end of the oxidation reactor through a fifth flow regulating valve, a liquid oxygen pump and a preprocessor in sequence.

[0019] Preferably, the gas-liquid separation unit includes a first cooler, a back pressure valve, a gas-liquid separation device, a gas collecting device and a liquid collecting device;

[0020] The input end of the first cooler is connected to the output end of the heat exchanger; the output end of the first cooler is connected to the input end of the back pressure valve, the output end of the back pressure valve is connected to the input end of the gas-liquid separation device, the gas output end of the gas-liquid separation device is connected to the gas collection device, and the liquid output end of the gas-liquid separation device is connected to the liquid collection device.

[0021] Preferably, the heat circulation loop unit includes a flow pump, a heat supply device, a second cooler and a seventh flow regulating valve;

[0022] The input end of the heating device is connected to the output end of the heat exchanger. The output end of the heating device is provided with two branches, one of which is used to supply heat to the outside world, and the other branch is connected to the input end of the heat exchanger via the second cooler, the seventh flow regulating valve and the flow pump in sequence to form a heat circulation loop.

[0023] Preferably, a residue collector is further included, and the input end of the residue collector is provided with two branches, one of which is connected to the output end of the first-stage gasification reactor, and the other is connected to the output end of the second-stage gasification reactor.

[0024] Preferably, there is a gap between the cylinder walls of the primary gasification reactor, the oxidation reactor and the secondary gasification reactor, and the gap is a product flow channel; wherein the liquid input end and the slurry input end of the primary gasification reactor are both arranged at the top of the primary gasification reactor, the slurry input end of the secondary gasification reactor is arranged at the top of the secondary gasification reactor, and the input end of the oxidation reactor is arranged at the top of the oxidation reactor.

[0025] In a second aspect, the present invention further provides a supercritical water gasification method for treating plastic waste slurry, based on the above-mentioned supercritical water gasification system for treating plastic waste slurry, comprising the following steps:

[0026] Water flows into the primary gasification reactor through one branch of the water preheating output unit; at the same time, another branch of the water preheating output unit flows into the slurry output unit, mixes with the plastic waste slurry input into the slurry output unit, and then flows into the primary gasification reactor and the secondary gasification reactor respectively;

[0027] Liquid oxygen is input into the oxidation reactor through a liquid oxygen output unit;

[0028] Water and plastic waste slurry enter the primary gasification reactor for primary gasification reaction, then enter the oxidation reactor for oxidation reaction, and finally enter the secondary gasification reactor for secondary gasification reaction to obtain gas-liquid products. The gas-liquid products flow out from the bottom of the secondary gasification reactor, pass through the heat exchanger for heat collection, and flow into the gas-liquid separation unit for gas-liquid separation. At the same time, the heat circulation loop unit is heated by the heat collected by the heat exchanger to form a heat circulation loop to supply heat to the outside world.

[0029] Compared with the prior art, the present invention has the following beneficial technical effects:

[0030] The present invention provides a supercritical water gasification system for treating plastic waste slurry. By coupling a primary gasification reactor, an oxidation reactor, and a secondary gasification reactor, an efficient gasification process is formed. This allows the plastic waste slurry to be gasified gradually at different reaction stages, improving gasification efficiency and conversion rate, thereby more effectively converting plastic waste into usable gas resources. A gap is formed between the bottom end of the oxidation reactor and the bottom end of the primary gasification reactor, and a through-hole is provided. A gap is also formed between the top end of the secondary gasification reactor and the top end of the oxidation reactor, and a through-hole is provided. This structural design facilitates gas circulation and mixing, promotes sufficient contact and reaction between the reactants, and improves gasification efficiency. The output ends of the water preheating output unit and the slurry output unit are each equipped with two branches, which can provide preheated water and slurry to the primary and secondary gasification reactors, respectively. The oxygen output unit is directly connected to the input end of the oxidation reactor, providing the necessary oxygen for the oxidation reaction. A heat exchanger is connected between the output end of the secondary gasification reactor and the gas-liquid separation unit to recover and utilize the heat energy generated during the gasification process. The setting of the heat circulation loop unit further improves the utilization efficiency of thermal energy, enables the system to supply heat to the outside world, and realizes the recycling of energy.

[0031] Furthermore, preheating the waterway with a solar heater not only reduces reliance on traditional energy sources, but also reduces energy consumption and operating costs. The first flow control valve allows precise adjustment of the amount of water entering the solar heater based on actual needs. The use of a water pump ensures a stable water flow in the waterway, preventing system instability caused by insufficient or fluctuating water pressure.

[0032] Furthermore, a mixer is used to thoroughly mix and homogenize the slurry before it enters the gasification reactor. This ensures an even distribution of plastic waste particles within the slurry, helping to improve gasification efficiency and reactor stability. A branch of the water tank is connected to the mixer's input to adjust the slurry's consistency and temperature, optimizing the pretreatment process.

[0033] Furthermore, the eighth flow regulating valve is located between the plastic waste slurry tank and the mixer, which can accurately control the flow of slurry entering the mixer to ensure a stable supply of slurry and uniform mixing. The sixth flow regulating valve is located between the water tank and the mixer, and is used to adjust the amount of water added to the mixer to adjust the consistency and fluidity of the slurry and optimize the slurry pretreatment process. The second flow regulating valve is located at the output end of the mixer, which can control the total amount of slurry flowing out of the mixer and provide a stable flow basis for subsequent distribution. The third and fourth flow regulating valves are respectively located on the branch lines from the output end of the mixer to the first plastic waste pump and the second plastic waste pump, which can accurately adjust the slurry flow entering the primary gasification reactor and the secondary gasification reactor to meet the needs of different reactors.

[0034] Furthermore, the fifth flow control valve allows for precise regulation of the liquid oxygen flow rate. The liquid oxygen pump, as a delivery device, ensures that the liquid oxygen can be stably and continuously delivered to the pre-processor and oxidation reactor with its efficient performance.

[0035] Furthermore, cooling the gas through the first cooler effectively reduces its temperature, thereby increasing the condensation rate of the liquid component in the gas. The back-pressure valve helps stabilize the pressure within the system. As the gas passes through the back-pressure valve, its pressure is effectively regulated, preventing system instability caused by pressure fluctuations. The gas-liquid separator efficiently separates the gas and liquid components.

[0036] Furthermore, the design of the heat circulation loop allows thermal energy to be recycled within the system. After the heating device extracts heat from the heat exchanger, a portion of the heat energy is used to provide heat to the outside world to meet production or living needs. The remaining heat energy is appropriately cooled by the secondary cooler before being pumped back to the heat exchanger for heating again, thus achieving continuous circulation and efficient utilization of thermal energy.

[0037] Furthermore, the residue collector can simultaneously receive residue output from both the primary and secondary gasification reactors. This ensures timely collection and processing of residue, avoids accumulation and blockage of residue within the system, and thus improves system operating efficiency and stability.

[0038] Furthermore, the gaps between the cylinder walls serve as product flow channels, ensuring smooth product flow between reactors. This design avoids product accumulation and blockage inside the reactor or in the connecting pipes, thereby improving the overall fluidity and operating efficiency of the system. The liquid input end and slurry input end of the first-stage gasification reactor are both arranged at the top of the first-stage gasification reactor, the slurry input end of the second-stage gasification reactor is arranged at the top of the second-stage gasification reactor, and the input end of the oxidation reactor is arranged at the top of the oxidation reactor, so that the liquid and slurry enter from the top of the first-stage gasification reactor to the bottom to complete the first-stage gasification reaction, then from the bottom of the oxidation reactor to the top to complete the oxidation reaction, and finally enter from the top of the second-stage gasification reactor to carry out the second-stage gasification reaction, which increases the reaction time of the product in each reaction process, allows the product to fully react, and improves the reaction efficiency.

[0039] The present invention also provides a supercritical water gasification method for treating plastic waste slurry. The oxidation reactor is embedded between two gasification reactors, distributing the plastic waste slurry between the primary and secondary gasification reactors. This reduces the treatment concentration of the plastic waste, ensures uniform mixing of the plastic waste material and water, and solves the gasification problem of high-concentration plastic waste slurry. While the gasification process absorbs heat and reduces the heat, the heat generated by the internal oxidation reactor is transferred to the primary gasification reactor through the tube wall, achieving heat transfer. Simultaneously, the heat generated by the oxidation reactor is transferred to the secondary gasification reactor, and reactants are fed into the secondary gasification reactor from the top of the secondary gasification reactor, achieving heat and mass transfer, effectively recovering the heat from the oxidation reactor, and achieving efficient energy matching. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of the principle structure of the supercritical water gasification system in an embodiment of the present invention;

[0041] In the figure: 1. Water tank; 2. First flow regulating valve; 3. Water pump; 4. Solar heater; 5. Mixer; 6. Second flow regulating valve; 7. Third flow regulating valve; 8. Fourth flow regulating valve; 9. First plastic waste pump; 10. Second plastic waste pump; 11. Pre-processor; 12. Liquid oxygen pump; 13. Fifth flow regulating valve; 14. Liquid oxygen tank; 15. Primary gasification reactor; 16. Oxidation reactor; 17. Secondary gasification reactor; 18. Residue collector; 19. Flow pump; 20. Heat exchanger; 21. First cooler; 22. Back pressure valve; 23. Gas-liquid separation device; 24. Gas collecting device; 25. Liquid collecting device; 26. Heating device; 27. Second cooler; 28. Plastic waste slurry tank; 29. ​​Sixth flow regulating valve; 30. Seventh flow regulating valve; 31. Eighth flow regulating valve. DETAILED DESCRIPTION

[0042] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0043] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0044] The purpose of the present invention is to provide a supercritical water gasification system and method for treating plastic waste slurry, so as to solve the technical problem in the prior art that high-concentration materials are difficult to efficiently gasify and efficiently provide heat in supercritical water.

[0045] The present invention is described in further detail below with reference to the accompanying drawings:

[0046] Example 1

[0047] See also Figure 1 In one embodiment of the present invention, a supercritical water gasification system for treating plastic waste slurry is provided, comprising a water preheating output unit, a slurry output unit, a liquid oxygen output unit, a coupled reactor device, a heat exchanger 20, a gas-liquid separation unit, and a heat circulation loop unit; the coupled reactor device comprises a primary gasification reactor 15, an oxidation reactor 16, and a secondary gasification reactor 17, which are sequentially arranged from the outside to the inside; a gap is formed between the bottom end of the oxidation reactor 16 and the bottom end of the primary gasification reactor 15, and a through hole is provided at the bottom end of the oxidation reactor 16; a gap is formed between the top end of the secondary gasification reactor 17 and the top end of the oxidation reactor 16, and the secondary gasification reactor 17 is A through hole is provided at the top of the reactor 17; the output end of the water preheating output unit is provided with two branches, one of which is connected to the liquid input end of the primary gasification reactor 15, and the other is connected to the slurry output unit; the output end of the slurry output unit is provided with two branches, one of which is connected to the slurry input end of the primary gasification reactor 15, and the other is connected to the slurry input end of the secondary gasification reactor 17; the output end of the liquid oxygen output unit is connected to the input end of the oxidation reactor 16, and the output end of the secondary gasification reactor 17 is connected to the gas-liquid separation unit via the heat exchanger 20; the heat circulation loop unit is arranged on the heat exchanger 20 for supplying heat to the outside world.

[0048] Preferably, the water preheating output unit includes a water tank 1, a first flow regulating valve 2, a water pump 3 and a solar heater 4; the output end of the water tank 1 is provided with two branches, one of which is connected to the liquid input end of the primary gasification reactor 15 through the first flow regulating valve 2, the water pump 3 and the solar heater 4 in sequence; the other branch is connected to the slurry output unit.

[0049] In this embodiment, a water tank 1 serves as a heat storage and output device, storing a certain amount of water. A first flow control valve 2 controls the flow of the medium through the pipeline, thereby achieving precise heat regulation. A water pump 3 provides power to circulate the water through the system. A solar heater 4 uses solar energy to heat the water, raising its temperature.

[0050] Among them, the slurry output unit includes a plastic waste slurry tank 28, a mixer 5, a first plastic waste pump 9 and a second plastic waste pump 10; the output end of the plastic waste slurry tank 28 is connected to the input end of the mixer 5, and a branch of the water tank 1 is connected to the input end of the mixer 5. The output end of the mixer 5 is provided with two branches, one of which is connected to the slurry input end of the primary gasification reactor 15 through the first plastic waste pump 9; the other branch is connected to the slurry input end of the secondary gasification reactor 17 through the second plastic waste pump 10.

[0051] In this embodiment, the plastic waste slurry tank 28 is used to store plastic waste slurry that has been pre-processed (such as crushing, cleaning, etc.). The mixer 5 is used to mix the plastic waste slurry with water to achieve the desired slurry concentration and uniformity.

[0052] Among them, an eighth flow regulating valve 31 is provided between the output end of the plastic waste slurry tank 28 and the input end of the mixer 5; a sixth flow regulating valve 29 is provided between a branch of the water tank 1 and the input end of the mixer 5; a second flow regulating valve 6 is provided at the output end of the mixer 5; a third flow regulating valve 7 is provided between a branch of the output end of the mixer 5 and the first plastic waste pump 9; a fourth flow regulating valve 8 is provided between another branch of the output end of the mixer 5 and the second plastic waste pump 10.

[0053] Specifically, the liquid oxygen output unit includes a preprocessor 11, a liquid oxygen pump 12, a fifth flow regulating valve 13 and a liquid oxygen tank 14; the output end of the liquid oxygen tank 14 is connected to the input end of the oxidation reactor 16 through the fifth flow regulating valve 13, the liquid oxygen pump 12 and the preprocessor 11 in sequence.

[0054] In this embodiment, the liquid oxygen tank 14 stores liquid oxygen and serves as the starting point for the liquid oxygen output unit. A fifth flow control valve 13, located at the output end of the liquid oxygen tank 14, regulates the flow of liquid oxygen to ensure stable operation of subsequent steps. The liquid oxygen pump 12 pressurizes the liquid oxygen, enabling it to overcome pipeline resistance and be smoothly delivered to the preprocessor 11. The preprocessor 11 pre-treats the liquid oxygen, including adjusting its temperature, to ensure that it meets the requirements of the oxidation reactor 16.

[0055] Specifically, the gas-liquid separation unit includes a first cooler 21, a back pressure valve 22, a gas-liquid separation device 23, a gas collecting device 24 and a liquid collecting device 25; the input end of the first cooler 21 is connected to the output end of the heat exchanger 20; the output end of the first cooler 21 is connected to the input end of the back pressure valve 22, the output end of the back pressure valve 22 is connected to the input end of the gas-liquid separation device 23, the gas output end of the gas-liquid separation device 23 is connected to the gas collecting device 24, and the liquid output end of the gas-liquid separation device 23 is connected to the liquid collecting device 25.

[0056] In this embodiment, the first cooler 21 is used to cool the high-temperature medium output from the heat exchanger 20, reduce its temperature, and make the gas-liquid mixture easier to separate. The back pressure valve 22 adjusts the pressure of the medium after it flows out of the first cooler 21 to ensure that the gas-liquid separation device 23 can operate under appropriate pressure conditions. The gas-liquid separation device 23 uses the density difference between gas and liquid and the dynamic effect of the fluid to separate the gas and liquid in the medium. The gas collection device 24 collects the gas separated from the gas-liquid separation device 23 for subsequent use or treatment. The liquid collection device 25 collects the liquid separated from the gas-liquid separation device 23, also for subsequent use or treatment.

[0057] Specifically, the heat circulation loop unit includes a flow pump 19, a heat supply device 26, a second cooler 27 and a seventh flow regulating valve 30; the input end of the heat supply device 26 is connected to the output end of the heat exchanger 20, and the output end of the heat supply device 26 is provided with two branches, one of which is used to supply heat to the outside, and the other branch is connected to the input end of the heat exchanger 20 via the second cooler 27, the seventh flow regulating valve 30 and the flow pump 19 in sequence to form a heat circulation loop.

[0058] In this embodiment, the heat circulation loop design allows thermal energy to be recycled within the system. After heat is extracted from heat exchanger 20 by heating device 26, a portion of the heat is used to heat the outside world, meeting production or living needs. The remaining heat is then appropriately cooled by second cooler 27 before being returned to heat exchanger 20 via flow pump 19 for further heating. This achieves continuous circulation and efficient utilization of thermal energy.

[0059] Specifically, the system further includes a residue collector 18 , the input end of the residue collector 18 is provided with two branches, one branch is connected to the output end of the primary gasification reactor 15 , and the other branch is connected to the output end of the secondary gasification reactor 17 .

[0060] Specifically, there is a gap between the cylinder walls of the primary gasification reactor 15, the oxidation reactor 16 and the secondary gasification reactor 17, and the gap is a product flow channel; the liquid input end and the slurry input end of the primary gasification reactor 15 are both arranged at the top of the primary gasification reactor 15, the slurry input end of the secondary gasification reactor 17 is arranged at the top of the secondary gasification reactor 17, and the input end of the oxidation reactor 16 is arranged at the top of the oxidation reactor 16.

[0061] In this embodiment, the gap between the cylinder walls serves as a product flow channel, which can ensure the smooth flow of products between the reactors. This design avoids the accumulation and blockage of products inside the reactor or in the connecting pipes, thereby improving the overall fluidity and operating efficiency of the system; the liquid input end and the slurry input end of the first-level gasification reactor 15 are both arranged at the top of the first-level gasification reactor 15, the slurry input end of the second-level gasification reactor 17 is arranged at the top of the second-level gasification reactor 17, and the input end of the oxidation reactor 16 is arranged at the top of the oxidation reactor 16, so that the liquid and slurry enter from the top of the first-level gasification reactor 15 to the bottom to complete the first-level gasification reaction, and then from the bottom to the top of the oxidation reactor 16 to complete the oxidation reaction, and finally enter from the top of the second-level gasification reactor 17 to carry out the second-level gasification reaction, which increases the reaction time of the product in each reaction process, so that the product can fully react and improve the reaction efficiency.

[0062] In summary, the present invention provides a supercritical water gasification system for treating plastic waste slurry. By coupling the primary gasification reactor 15, the oxidation reactor 16, and the secondary gasification reactor 17, an efficient gasification treatment process is formed, so that the plastic waste slurry can be gradually gasified at different reaction stages, improving the gasification efficiency and conversion rate, thereby more effectively converting plastic waste into usable gas resources. The bottom end of the oxidation reactor 16 is set with a gap between the bottom end of the primary gasification reactor 15 and the bottom end, and a through hole is provided. At the same time, the top end of the secondary gasification reactor 17 is also set with a gap between the top end of the oxidation reactor 16 and the top end of the oxidation reactor 16 and a through hole is provided. This structural design is conducive to the circulation and mixing of gases, promotes sufficient contact and reaction between reactants, and improves gasification efficiency. The output ends of the water preheating output unit and the slurry output unit are both branched, which can provide preheated water and slurry to the primary gasification reactor 15 and the secondary gasification reactor 17 respectively. The oxygen output unit is directly connected to the input end of the oxidation reactor 16 to provide the necessary oxygen for the oxidation reaction. Heat exchanger 20, connected between the output of secondary gasification reactor 17 and the gas-liquid separation unit, is used to recover and utilize the heat generated during the gasification process. The thermal cycle unit further improves the efficiency of thermal energy utilization, enabling the system to supply heat to the outside world and achieve energy recycling.

[0063] Example 2

[0064] In one embodiment of the present invention, a supercritical water gasification method for treating plastic waste slurry is provided. Based on the above-mentioned supercritical water gasification system for treating plastic waste slurry, the method comprises the following steps:

[0065] 1) Open the first flow regulating valve 2 to increase the pressure of the water in the water tank 1 through the water pump 3 , then heat it through the solar heater 4 , and then flow into the primary gasification reactor 15 through the pipe wall 34 .

[0066] 2) Open the sixth flow regulating valve 29 and the eighth flow regulating valve 31 to allow the water in the water tank 1 and the material in the plastic waste slurry tank 28 to enter the mixer 5 at the same time for sufficient mixing. Then, open the second flow regulating valve 6, the third flow regulating valve 7 and the fourth flow regulating valve 8. After being pressurized by the first plastic waste pump 9 and the second plastic waste pump 10 respectively, the water is input into the primary gasification reactor 15 and the secondary gasification reactor 17.

[0067] 3) Open the fifth flow control valve 13. The liquid oxygen in the liquid oxygen tank 14 is pressurized by the liquid oxygen pump 12, then heated by the pre-processor 11 and fed into the oxidation reactor 16.

[0068] 4) After the plastic waste and water enter the primary gasification reactor 15 for reaction, they enter the oxidation reactor 16 for oxidation, and then enter the secondary gasification reactor 17 for gasification, realizing staged gasification.

[0069] 5) The residues after the reaction in the primary gasification reactor 15 and the secondary gasification reactor 17 are collected by the residue collector 18 .

[0070] 6) The gas and liquid after the reaction flow out from the bottom of the secondary gasification reactor 17, pass through the heat exchanger 20 for heat collection, and after cooling through the first cooler 21, the back pressure valve 22 is opened to flow into the gas-liquid separation device 23 for gas-liquid separation. The separated gas enters the gas collection device 24 for collection, and the separated liquid enters the liquid collection device 25 for collection.

[0071] 7) After the water in the heating device 26 is cooled by the second cooler 27, the seventh flow regulating valve 30 is opened and the water flows into the flow pump 19 for pressurization. The water is then heated by the heat collected by the heat exchanger 20 and input into the heating device 26 and then into each household for heating, realizing resource utilization.

[0072] In summary, the present invention also provides a supercritical water gasification method for treating plastic waste slurry, in which the oxidation reactor 16 is embedded between the two gasification reactors, so that the plastic waste slurry is distributed between the primary and secondary gasification reactors 17, reducing the treatment concentration of the plastic waste, ensuring the uniform mixing of the plastic waste material and water, and solving the gasification problem of high-concentration plastic waste slurry. While the gasification process is endothermic reduction, the heat generated by the internal oxidation reactor 16 is transferred to the primary gasification reactor 15 through the pipe wall to achieve heat transfer; at the same time, the heat generated by the oxidation reactor 16 is transferred to the secondary gasification reactor 17 and the reactants are input into the secondary gasification reactor 17 from the top of the secondary gasification reactor 17, achieving heat and mass transfer, effectively recovering the heat of the oxidation reactor 16, and achieving efficient energy matching.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the present invention.

Claims

1. A supercritical water gasification system for treating plastic waste slurry, characterized in that: It includes a water preheating output unit, a slurry output unit, a liquid oxygen output unit, a coupled reactor device, a heat exchanger (20), a gas-liquid separation unit, and a heat circulation loop unit; The coupled reactor device comprises a primary gasification reactor (15), an oxidation reactor (16), and a secondary gasification reactor (17) which are sequentially arranged from the outside to the inside; a gap is provided between the bottom end of the oxidation reactor (16) and the bottom end of the primary gasification reactor (15), and a through hole is provided at the bottom end of the oxidation reactor (16); a gap is provided between the top end of the secondary gasification reactor (17) and the top end of the oxidation reactor (16), and a through hole is provided at the top end of the secondary gasification reactor (17); There is a gap between the walls of the primary gasification reactor (15), the oxidation reactor (16), and the secondary gasification reactor (17), and the gap is a product flow channel; wherein the liquid input end and the slurry input end of the primary gasification reactor (15) are both arranged at the top of the primary gasification reactor (15), the slurry input end of the secondary gasification reactor (17) is arranged at the top of the secondary gasification reactor (17), and the input end of the oxidation reactor (16) is arranged at the top of the oxidation reactor (16); The output end of the water preheating output unit is provided with two branches, one of which is connected to the liquid input end of the first-stage gasification reactor (15), and the other is connected to the slurry output unit; the output end of the slurry output unit is provided with two branches, one of which is connected to the slurry input end of the first-stage gasification reactor (15), and the other is connected to the slurry input end of the second-stage gasification reactor (17); The output end of the liquid oxygen output unit is connected to the input end of the oxidation reactor (16), and the output end of the secondary gasification reactor (17) is connected to the gas-liquid separation unit via the heat exchanger (20); the heat circulation loop unit is arranged on the heat exchanger (20) for supplying heat to the outside.

2. A supercritical water gasification system for treating plastic waste slurry according to claim 1, characterized in that: The water circuit preheating output unit comprises a water tank (1), a first flow regulating valve (2), a water pump (3) and a solar heater (4); The output end of the water tank (1) is provided with two branches, one of which is connected to the liquid input end of the primary gasification reactor (15) through a first flow regulating valve (2), a water pump (3) and a solar heater (4) in sequence; the other branch is connected to a slurry output unit.

3. A supercritical water gasification system for treating plastic waste slurry according to claim 2, characterized in that: The slurry output unit comprises a plastic waste slurry tank (28), a mixer (5), a first plastic waste pump (9), and a second plastic waste pump (10); The output end of the plastic waste slurry tank (28) is connected to the input end of the mixer (5), and a branch of the water tank (1) is connected to the input end of the mixer (5). The output end of the mixer (5) is provided with two branches, one of which is connected to the slurry input end of the primary gasification reactor (15) via a first plastic waste pump (9); and the other branch is connected to the slurry input end of the secondary gasification reactor (17) via a second plastic waste pump (10).

4. A supercritical water gasification system for treating plastic waste slurry according to claim 3, characterized in that: An eighth flow regulating valve (31) is provided between the output end of the plastic waste slurry tank (28) and the input end of the mixer (5); a sixth flow regulating valve (29) is provided between a branch of the water tank (1) and the input end of the mixer (5); a second flow regulating valve (6) is provided at the output end of the mixer (5); a third flow regulating valve (7) is provided between a branch of the output end of the mixer (5) and the first plastic waste pump (9); and a fourth flow regulating valve (8) is provided between another branch of the output end of the mixer (5) and the second plastic waste pump (10).

5. The supercritical water gasification system for treating plastic waste slurry according to claim 1, characterized in that: The liquid oxygen output unit includes a preprocessor (11), a liquid oxygen pump (12), a fifth flow regulating valve (13) and a liquid oxygen tank (14); The output end of the liquid oxygen tank (14) is connected to the input end of the oxidation reactor (16) through the fifth flow regulating valve (13), the liquid oxygen pump (12) and the pre-processor (11) in sequence.

6. The supercritical water gasification system for treating plastic waste slurry according to claim 1, characterized in that: The gas-liquid separation unit comprises a first cooler (21), a back pressure valve (22), a gas-liquid separation device (23), a gas collecting device (24), and a liquid collecting device (25); The input end of the first cooler (21) is connected to the output end of the heat exchanger (20); the output end of the first cooler (21) is connected to the input end of the back pressure valve (22); the output end of the back pressure valve (22) is connected to the input end of the gas-liquid separation device (23); the gas output end of the gas-liquid separation device (23) is connected to the gas collecting device (24); and the liquid output end of the gas-liquid separation device (23) is connected to the liquid collecting device (25).

7. The supercritical water gasification system for treating plastic waste slurry according to claim 1, characterized in that: The heat circulation loop unit includes a flow pump (19), a heat supply device (26), a second cooler (27), and a seventh flow regulating valve (30); The input end of the heating device (26) is connected to the output end of the heat exchanger (20). The output end of the heating device (26) is provided with two branches, one of which is used to supply heat to the outside, and the other branch is connected to the input end of the heat exchanger (20) via the second cooler (27), the seventh flow regulating valve (30) and the flow pump (19) in sequence, thereby forming a heat circulation loop.

8. The supercritical water gasification system for treating plastic waste slurry according to claim 1, characterized in that: It also includes a residue collector (18), wherein the input end of the residue collector (18) is provided with two branches, one of which is connected to the output end of the first-stage gasification reactor (15), and the other is connected to the output end of the second-stage gasification reactor (17).

9. A supercritical water gasification method for treating plastic waste slurry, characterized in that: A supercritical water gasification system for treating plastic waste slurry according to any one of claims 1 to 8 comprises the following steps: Water flows into the primary gasification reactor (15) through a branch of the water preheating output unit; at the same time, another branch of the water preheating output unit flows into the slurry output unit, is mixed with the plastic waste slurry input into the slurry output unit, and then flows into the primary gasification reactor (15) and the secondary gasification reactor (17) respectively; Liquid oxygen is input into the oxidation reactor (16) through the liquid oxygen output unit; The water and plastic waste slurry enters the primary gasification reactor (15) for a primary gasification reaction, then enters the oxidation reactor (16) for an oxidation reaction, and finally enters the secondary gasification reactor (17) for a secondary gasification reaction to obtain gas-liquid products. The gas-liquid products flow out from the bottom of the secondary gasification reactor (17), pass through the heat exchanger (20) for heat collection, and flow into the gas-liquid separation unit for gas-liquid separation. At the same time, the heat circulation loop unit is heated by the heat collected by the heat exchanger (20) to form a heat circulation loop, thereby supplying heat to the outside.

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